Mounting structure of oil control valve unit and motorcycle

ABSTRACT

There is provided a mounting structure of an oil control valve unit configured to control a hydraulic pressure to a variable valve timing device of an engine. The engine is supported by a vehicle body frame. A heat exchanger is mounted in front of the engine. The oil control valve unit is mounted at a side of the engine. A part of the vehicle body frame is arranged between the oil control valve unit and the heat exchanger in a front and rear direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2017-087922 filed onApr. 27, 2017, including specification, drawings and claims isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a mounting structure of an oil controlvalve unit configured to control a hydraulic pressure to a variablevalve timing device, and a motorcycle.

BACKGROUND

In recent years, engines in which a variable valve timing deviceconfigured to control valve timings of an intake valve and an exhaustvalve in correspondence to a driving state of an engine is mounted forhigh output, low-fuel consumption and low exhaust gas have beenincreasingly used. In this type of engines, an engine has been known inwhich a hydraulic pressure to the variable valve timing device iscontrolled with an oil control valve unit provided between a cylinderhead and a radiator (for example, refer to Patent Document 1). The oilcontrolled by the oil control valve unit is supplied to an advancechamber and a retard chamber of the variable valve timing device, and arotation phase of a camshaft relative to a crankshaft is changed, sothat the valve timing is adjusted.

Patent Document 1: Japanese Patent No. 5345448B

However, according to Patent Document 1, since the oil control valveunit is mounted in the vicinity of the radiator (heat exchanger),operation characteristics of the oil control valve unit are susceptibleto heat from the radiator. Further, since the oil control valve unit ismounted to protrude laterally from the radiator so that it can beexposed to traveling wind, it is not possible to protect the oil controlvalve unit from flying stones in front of a vehicle body.

SUMMARY

It is therefore one of objects of the present invention to provide amounting structure of an oil control valve unit capable of suppressingoperation characteristics of the oil control valve unit from beingdeteriorated due to an increase in temperature and protecting the oilcontrol valve unit from flying stones in front of a vehicle body, and amotorcycle.

According to an aspect of the embodiments of the present invention,there is provided a mounting structure of an oil control valve unitconfigured to control a hydraulic pressure to a variable valve timingdevice of an engine, wherein the engine is supported by a vehicle bodyframe, a heat exchanger is mounted in front of the engine, the oilcontrol valve unit is mounted at a side of the engine, and a part of thevehicle body frame is arranged between the oil control valve unit andthe heat exchanger in a front and rear direction.

According to the mounting structure of the oil control valve unit of oneaspect of the present invention, the part of the vehicle body frame ispositioned between the heat exchanger and the oil control valve unit,and heat from the heat exchanger is shielded by the part of the vehiclebody frame, so that operation characteristics of the oil control valveunit are suppressed from being deteriorated due to an increase intemperature. Also, the oil control valve unit is protected from flyingstones in front of the vehicle body by the part of the vehicle bodyframe.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a left side view of a motorcycle of an illustrativeembodiment;

FIG. 2 is a peripheral perspective view of an engine of the illustrativeembodiment;

FIG. 3 is a right side view of a front half part of the motorcycle ofthe illustrative embodiment;

FIG. 4 is a peripheral rear view of the engine of the illustrativeembodiment;

FIGS. 5A and 5B are pictorial views of an oil control valve unit of theillustrative embodiment;

FIGS. 6A and 6B are a perspective view and a bottom view of a valvehousing of the illustrative embodiment;

FIG. 7 is a side view of a cylinder of the illustrative embodiment;

FIG. 8 is a sectional view taken along a line A-A of FIG. 7;

FIG. 9 is a pictorial view of a variable valve timing system of theillustrative embodiment;

FIG. 10 depicts an example of an operation of mounting a vehicle bodyframe of the illustrative embodiment; and

FIG. 11 depicts another example of the operation of mounting the vehiclebody frame of the illustrative embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an illustrative embodiment will be described in detail withreference to the accompanying drawings. Herein, an example where amounting structure of an oil control valve unit of the illustrativeembodiment is applied to a sport-type motorcycle will be described.However, the target to which the present invention is applied is notlimited thereto, and can be appropriately changed. For example, themounting structure of the oil control valve unit can be applied to othertypes of motorcycles. FIG. 1 is a left side view of the motorcycle ofthe illustrative embodiment. In the drawings, the front of the vehiclebody is denoted with an arrow FR, the rear of the vehicle body isdenoted with an arrow RE, the left of the vehicle body is denoted withL, and the right of the vehicle body is denoted with R.

As shown in FIG. 1, a motorcycle 1 is configured by mounting a varietyof components such as an engine 41, an electric system and the like to atwin spar-type vehicle body frame 10 made by aluminum casting. A mainframe 12 of the vehicle body frame 10 is branched rightward and leftwardfrom a head pipe 11 and extends rearward. The pair of right and leftmain frames 12 is bent to turn around toward the rear of the engine 41,and a rear side of the engine 41 is supported at rear parts (body frames15) of the main frames 12. A down frame 13 (refer to FIG. 2) of thevehicle body frame 10 is branched rightward and leftward from the headpipe 11 and extends downward. A front side of the engine 14 is supportedat lower parts of the pair of right and left down frames 13.

A part of the front part of the main frame 12 is configured as a tankrail 14, and a fuel tank 21 is mounted on the tank rail 14. The rearpart of the main frame 12 is configured as a body frame 15. The bodyframe 15 is formed at a substantially intermediate position thereof in avertical direction with a swing arm pivot 17 configured to swingablysupport a swing arm 18. A seat rail (not shown) and a back stay 16extending rearward are provided above the body frame 15. The seat railis provided thereon with a rider seat 23 and a pillion seat 24 in thevicinity of the fuel tank 21.

The vehicle body frame 10 is mounted with a variety of covers asexternal packages of a vehicle body. For example, a front half part ofthe vehicle body is covered with a front cowl 26, a side surface of thevehicle body is covered with a side cowl 27. Also, the seat rail iscovered with a rear cowl 28, and a front lower part of the engine 41 iscovered with an under cowl 29. A pair of right and left front forks 32is supported to be steerable to the head pipe 11 via a steering shaft(not shown). The front forks 32 have front suspensions for front wheelbuffering embedded therein. A front wheel 33 is rotatably supported bylower parts of the front forks 32, and the upper of the front wheel 33is covered with a front fender 34.

The swing arm 18 extends rearward from the swing arm pivot 17. A rearsuspension 36 for rear wheel buffering is provided between the swing arm18 and the body frame 15. The rear suspension 36 has one end supportedby an upper end-side of the body frame 15 and the other end coupled tothe swing arm 18 via a suspension link 37. A rear wheel 38 is rotatablysupported by a rear end of the swing arm 18. The engine 41 and the rearwheel 38 are coupled via a deceleration mechanism. The power from theengine 41 is transmitted to the rear wheel 38 via the decelerationmechanism. The upper of the rear wheel 38 is covered with a rear fender39 provided at a rear part of the rear cowl 28.

The engine 41 is configured by mounting a cylinder 43 (refer to FIG. 2)on an engine case 42 in which a crankshaft (not shown) of a parallelfour-cylinder engine and the like are accommodated. The engine 41 issupported by the vehicle body frame 10, so that the rigidity of theentire vehicle body is secured. The air is taken into the engine 41through an intake pipe (not shown), and the air and fuel are mixed andsupplied to a combustion chamber by a fuel injection device. An exhaustgas after combustion is discharged from a muffler 44 via an exhaust pipe(not shown) extending rearward on a right surface of the engine 41.

For the engine 41 configured as described above, a variable valve timingsystem configured to control driving timings of an intake valve and anexhaust valve in correspondence to a driving state of the engine isadopted. In the variable valve timing system, the engine 41 is providedwith an oil control valve unit. However, the oil control valve unitcannot be freely mounted. For example, a mounting space is limited dueto diverse factors such as an influence of heat from the radiator, apressure loss in an oil passage, interference upon mounting of thevehicle body frame 10, interference upon mounting of a cam chain in theengine 41, and the like.

As shown in FIG. 2, a radiator 47 is usually mounted in front of theengine 41, and operation characteristics of an oil control valve unit 61are susceptible to heat from the radiator 47, depending on a mountingposition of the oil control valve unit 61. Therefore, in the mountingstructure of the oil control valve unit 61 of the illustrativeembodiment, the heat from the radiator 47 is shielded in front of theoil control valve unit 61 by a part of the vehicle body frame 10. Also,since the traveling wind is also shielded by the vehicle body frame 10,the oil control valve unit 61 is exposed so as to avoid heat retention,as seen from rear, so that the air flow is not hindered.

Also, depending on the mounting position of the oil control valve unit61, an oil passage in the engine 41 is complex, so that a pressure lossincreases. As a result, it is not possible to supply the oil to the oilcontrol valve unit 61 with a sufficient hydraulic pressure. Therefore,in the mounting structure of the oil control valve unit 61 of theillustrative embodiment, a main gallery 53 in the engine 41 and the oilcontrol valve unit 61 are connected by an external piping 81, so thatthe oil is directly supplied from the main gallery 53 to the oil controlvalve unit 61. Also, the external piping 81 is configured to bypass aninside of the engine 41, so that a structure of the oil passage in theengine 41 is simplified.

Also, depending on the mounting position of the oil control valve unit61, the oil control valve unit 61 becomes an obstacle upon mounting ofthe vehicle body frame 10 or upon a cam chain 56 (refer to FIG. 9) inthe engine 41. Therefore, in the mounting structure of the oil controlvalve unit 61 of the illustrative embodiment, the oil control valve unit61 is detachably mounted to an outer surface of the engine 41. After thevehicle body frame 10 is mounted to the engine 41 or the cam chain 56 inthe engine 41 is mounted, the oil control valve unit 61 is then mounted,so that it is possible to secure a degree of mounting freedom of the oilcontrol valve unit 61.

In the below, the mounting structure of the oil control valve unit ofthe illustrative embodiment is described with reference to FIGS. 2 to5B. FIG. 2 is a peripheral perspective view of the engine of theillustrative embodiment. FIG. 3 is a right side view of a front halfpart of the motorcycle of the illustrative embodiment. FIG. 4 is aperipheral rear view of the engine of the illustrative embodiment. FIGS.5A and 5B are pictorial views of the oil control valve unit of theillustrative embodiment. In the meantime, in FIGS. 2 to 5B, forconvenience of descriptions, a variety of covers as external packages ofthe vehicle body are omitted.

As shown in FIGS. 2 and 3, the engine 41 is supported by the vehiclebody frame 10, and the radiator 47 is mounted in front of the engine 41.As described above, the engine 41 is provided with the cylinder 43 onthe engine case 42. The pair of right and left main frames 12 extendsrearward from the head pipe 11 above the cylinder 43, and the pair ofright and left down frames 13 extends downward from the head pipe 11 infront of the cylinder 43. The front part of the vehicle body frame 10 isbifurcated into the main frames 12 and the down frames 13, so that amounting space 49 of the oil control valve unit 61 is secured at a side(right side) of the cylinder 43.

In this case, the down frames 13 are configured to support a front sideof the engine 41. More specifically, the down frames 13 are configuredto support a front side of the cylinder 43, and have a substantiallytriangular shape in which a width of the down frame 13 becomes widergradually from a support position 19 to the engine 41 toward the headpipe 11. The cylinder 43 provided at the upper part of the engine 41 issupported with the down frames 13, so that it is possible to suppressthe width of the down frame 13 from being widened in the front and reardirection and to secure the mounting space 49 of the oil control valveunit 61 at a side of the cylinder 43, unlike a structure in which alower part of the engine 41 is supported with the down frames 13.

At a side of the engine 41, the oil control valve unit 61 is mounted inthe mounting space 49 between the main frame 12 and the down frame 13,so that a space between the radiator 47 and the oil control valve unit61 is blocked by the down frame 13. Thereby, the heat from the radiator47 is shielded by the down frame 13, which is a part of the vehicle bodyframe 10, so that the deterioration of the operation characteristics ofthe oil control valve unit 61 due to an increase in temperature issuppressed. Also, the oil control valve unit 61 is positioned betweenthe main frame 12 and the down frame 13, so that the oil control valveunit 61 is protected from flying stones in front of the vehicle body.

Since the front of the oil control valve unit 61 is blocked by the downframe 13, the influence of heat from the radiator 47 is suppressed.However, the traveling wind is difficult to collide with the oil controlvalve unit 61. For this reason, regarding a pair of front and rear INcam axis center O1 and EX cam axis center O2 of the cylinder 43, thedown frame 13 is configured to pass through a front side of the EX camaxis center O2 and the main frame 12 is configured to pass through arear side of the IN cam axis center O1, so that the mounting space 49 ofthe oil control valve unit 61 is widened. The mounting space 49 iswidened, so that the heat is difficult to be retained in the mountingspace 49 and a surrounding temperature is thus lowered.

Also, a transmission is accommodated in the engine case 42, and theengine case 42 is provided with a transmission cover 45 to cover thetransmission from a side. The transmission cover 45 bulges laterally,and the oil control valve unit 61 is mounted above the transmissioncover 45. The oil control valve unit 61 is surrounded by thetransmission cover 45, the main frame 12, and the down frame 13, and aspace surrounded by the transmission cover 45, the main frame 12 and thedown frame 13 is effectively utilized as the mounting space 49. Thereby,the oil control valve unit 61 is protected from the flying stones infront of the vehicle body by the down frame 13, and the oil controlvalve unit 61 is protected from flying stones below the vehicle body bythe transmission cover 45.

An upper part of the transmission cover 45 is formed so that an intervalwith the oil control valve unit 61 becomes wider forward. The upper partof the transmission cover 45 is inclined obliquely downward toward thefront, and a vertical interval between the upper part of thetransmission cover 45 and the oil control valve unit 61 is increased.The transmission cover 45 and the oil control valve unit 61 are spacedfrom each other, so that the mounting space 49 of the oil control valveunit 61 can be widened, the heat is difficult to be retained in themounting space 49 and the surrounding temperature is thus lowered. Inthis way, the mounting space 49 having a sufficient area is secured atthe side of the engine 41 by the main frame 12, the down frame 13 andthe transmission cover 45.

The pair of right and left main frames 12 extends obliquely rearwardfrom the head pipe 11, and a facing interval of the main frames 12 isnarrowed at the rear of the mounting space 49 of the oil control valveunit 61 (particularly, refer to FIG. 4). Also, the oil control valveunit 61 is mounted above the transmission cover 45. Thereby, the airflow is not hindered at the rear of the oil control valve unit 61 by themain frames 12 and the transmission cover 45. The oil control valve unit61 is exposed, as seen from the rear. Therefore, upon the traveling, theheat flows rearward from the mounting space 49, so that the oil controlvalve unit 61 is effectively cooled.

Also, a radiator hose 48 extends rearward from the radiator 47, and theoil control valve unit 61 is mounted above the radiator hose 48 at theside of the engine 41. The cooling water is supplied from the radiator47 to the engine 41 by the radiator hose 48, and the oil control valveunit 61 is cooled by the cooling water in the radiator hose 48. Sincethe radiator hose 48 traverses immediately below the oil control valveunit 61, the oil control valve unit 61 is protected from flying stonesbelow the vehicle body by the radiator hose 48. Since the radiator hose48 is formed of rubber or the like, the radiator hose 48 is difficult tobe damaged due to the flying stones.

As shown in FIGS. 2 and 4, the oil control valve unit 61 overlaps themain frame 12, as seen from above, and overlaps the down frame 13 andthe transmission cover 45, as seen from the front and rear direction.The oil control valve unit 61 overlaps the main frame 12, as seen fromabove, so that the main frame 12 functions as a rain shelter and adamage of the oil control valve unit 61 due to the rainwater isprevented. The oil control valve unit 61 overlaps the down frame 13 andthe transmission cover 45, as seen from the front and rear direction, sothat the oil control valve unit 61 is protected from flying stones infront of the vehicle body and below the vehicle body, and the effect ofshielding the heat from the radiator 47 by the down frame 13 isincreased.

The oil control valve unit 61 is mounted at a more inner side than allof the transmission cover 45, the main frame 12 and the down frame 13,as seen from the front and rear direction. The oil control valve unit 61is protected from a shock upon turnover of the vehicle body and theother external shock by the transmission cover 45, the main frame 12 andthe down frame 13. Also, the oil control valve unit 61 is accommodatedin the vehicle body frame 10, as seen from the front and rear direction,so that an increase in entire vehicle width dimension of the vehiclebody is suppressed. In the meantime, the inner side as seen from thefront and rear direction may be a more inner side than the outermostsurfaces of the transmission cover 45, the main frame 12 and the downframe 13.

Returning to FIGS. 2 and 3, the engine 41 is formed therein with themain gallery 53 to which the oil is to be supplied from an oil pump 52(refer to FIG. 9), and the main gallery 53 and the oil control valveunit 61 are connected by one external piping 81. Thereby, the oil isdirectly supplied from the main gallery 53 in which the hydraulicpressure is high to the oil control valve unit 61 through the externalpiping 81. The oil is supplied from the main gallery 53 to the oilcontrol valve unit 61 without via the oil passage in the engine 41, sothat it is possible to suppress the pressure loss and to supply the oilof the high hydraulic pressure to the oil control valve unit 61.

The external piping 81 extends forward from the main gallery 53 belowthe transmission cover 45, turns around the transmission cover 45 frombelow and then extends upward. The external piping 81 passes through aninner side of the radiator hose 48, as seen from the front and reardirection, passes through between the oil control valve unit 61 and thedown frame 13 and is then connected to the oil control valve unit 61. Inthis case, the oil control valve unit 61 is mounted at the rear of theEX cam axis center O2, and a mounting route of the external piping 81 issecured between the oil control valve unit 61 and the down frame 13. Bythis mounting route, the increase in entire vehicle width dimension ofthe vehicle body is suppressed, and the external piping 81 is shortenedto suppress the pressure loss in the piping.

The external piping 81 passes through the inner side of the radiatorhose 48, as seen from the front and rear direction, and passes throughthe inner side of the vehicle body frame 10, as seen from the front andrear direction, so that the external piping 81 is protected from a shockupon turnover of the vehicle body and the other external shock by theradiator hose 48 and the vehicle body frame 10. Since a part of theexternal piping 81 overlaps the down frame 13, as seen from the frontand rear direction, and overlaps the radiator hose 48, as seen frombelow, the external piping 81 is protected from the flying stones in thefront of the vehicle body and below the vehicle body by the down frame13 and the radiator hose 48. In this way, the external piping 81 is alsosufficiently protected from the shock and flying stones, like the oilcontrol valve unit 61.

The oil control valve unit 61 is provided with an intake control valve62 configured to control an intake-side valve timing and an exhaustcontrol valve 63 configured to control an exhaust-side valve timing. Theoil control valve unit 61 is connected with the external piping 81, andthe intake control valve 62 and the exhaust control valve 63 arevertically spaced from each other with horizontal postures with aconnection part of the external piping 81 being interposed therebetween.Since the intake control valve 62 and the exhaust control valve 63 arespaced from each other, the heat is difficult to be retained between theintake control valve 62 and the exhaust control valve 63.

Also, since the intake control valve 62 and the exhaust control valve 63are vertically aligned, an increase in vehicle width dimension of a mainbody of the vehicle body is suppressed. Also, since the intake controlvalve 62 and the exhaust control valve 63 are longitudinally alignedwith horizontal postures, both the control valves 62, 63 are evenlycooled by the air flow upon the traveling. That is, like a configurationwhere the intake control valve 62 and the exhaust control valve 63 arehorizontally aligned with vertical postures, a situation where only afront control valve is cooled by the air flow and a rear control valveis difficult to be cooled does not occur.

As shown in FIG. 5A, the intake control valve 62 and the exhaust controlvalve 63 are a cylindrical solenoid valve, respectively, and arerespectively divided into a solenoid side in which a solenoid 65 isaccommodated and a valve spool side in which a valve spool 66 isaccommodated. The solenoid 65 is a so-called cylindrical conductivecoil, and is configured to generate a magnetic field by energization,thereby advancing and retreating the valve spool 66 coupled to an ironcore 70 in the solenoid 65. The valve spool 66 is advanced andretreated, so that an oil path is switched in the intake control valve62 and the exhaust control valve 63.

The intake control valve 62 and the exhaust control valve 63 are likelyto generate heat by the energization of the solenoids 65, and theoperation characteristics thereof are deteriorated due to increases intemperature of the solenoids 65. Therefore, in the illustrativeembodiment, the solenoids 65-side of the intake control valve 62 and theexhaust control valve 63 face rearward. Since the solenoids 65 arespaced from the radiator 47, the heat generation of the solenoids 65 issuppressed, so that the deterioration of the operation characteristicsof the solenoids 65 due to increases in temperature is suppressed. Also,axis centers of the solenoids 65 of the intake control valve 62 and theexhaust control valve 63 preferably face horizontally or obliquelyupward toward the rear.

For example, as shown in a comparative example of FIG. 5B, when the axiscenters of the solenoids 65 of the intake control valve 62 and theexhaust control valve 63 face obliquely downward toward the rear,foreign matters such as contaminations C generated at the valve spools66-side are conveyed toward the solenoids 65-side by the oil. For thisreason, the foreign matters such as contaminations C may be deposited atthe solenoids 65-side. For this reason, in the illustrative embodimentof FIG. 5A, since axis centers of the solenoids 65 face horizontally orobliquely upward toward the rear (horizontally, in FIG. 5A), a situationwhere the foreign matters such as contaminations C generated at thevalve spools 66-side enter and damage the solenoids 65-side isprevented.

Subsequently, the oil control valve unit is described in detail withreference to FIGS. 6A to 8. FIGS. 6A and 6B are a perspective view and abottom view of a valve housing of the illustrative embodiment. FIG. 7 isa side view of the cylinder of the illustrative embodiment. FIG. 8 is asectional view taken along a line A-A of FIG. 7. Meanwhile, in FIG. 6B,for convenience of descriptions, the solenoids-side are shown withdashed-two dotted line.

As shown in FIG. 6A, a valve housing 64 of the oil control valve unit 61is provided with a pair of support cases 68, in which the valve spools(not shown) are to be inserted, at an upper part of a housing main body67 having a plurality of oil passages aligned annularly. The valvehousing 64 is used with being inserted into an outer wall of thecylinder 43 (refer to FIG. 7), and an outer surface of the housing mainbody 67 is mounted with an O-ring 69 for sealing a gap between the outerwall of the cylinder 43 and the housing main body 67. Based on theO-ring 69 as a boundary, the housing main body 67-side is accommodatedin the cylinder 43, and the pair of support cases 68-side protrudesoutward from the cylinder 43.

The pair of support cases 68 is provided with horizontal postures on theupper part of the housing main body 67 of a vertical posture atpositions that face each other with an opening 71 of the housing mainbody 67 being interposed therebetween. The support cases 68 and thehousing main body 67 are reinforced with ribs 72 at four places aroundthe opening 71, and the ribs 72 are formed therein with oil passages(not shown) configured to connect insides of the support cases 68 and aninside of the housing main body 67. The ribs 72 continue from vicinitiesof both ends of each of the cylindrical support cases 68 along the upperpart of the housing main body 67, and are respectively inclined so thata lateral protrusion amount increases from the upper toward the lower. Aspace between the pair of support cases 68 is configured as a mountingspace of a banjo joint 82, which is a circular ring-shaped joint and isprovided at a leading end of the external piping 81, and an opening endof the housing main body 67 is formed with an annular seat surface 74 onwhich the banjo joint 82 is to be put.

Also, outer surfaces of the four ribs 72 of the valve housing 64 areformed with guide surfaces 75 configured to guide the banjo joint 82 tothe seat surface 74. The respective guide surfaces 75 face each otherwith the opening 71 of the housing main body 67 being interposedtherebetween, and are inclined so that a facing interval of the guidesurfaces 75, which face each other with the opening 71 being interposedtherebetween, becomes narrower from the upper toward the lower. Thebanjo joint 82 is slid and guided along the respective guide surfaces 75so that a mounting hole 83 of the banjo joint 82 coincides with theopening 71 of the valve housing 64. In the meantime, although describedin detail later, the banjo joint 82 and the valve housing 64 are mountedto the engine 41 from a side by a bolt 78 (refer to FIG. 7), and theexternal piping 81 and the oil passages of the valve housing 64communicate with each other via the banjo joint 82.

As shown in FIG. 6B, the housing main body 67 is formed with a pluralityof oil ports (oil channels) 76 so as to surround the opening 71. Therespective oil ports 76 are an input port, an advance port, a retardport, and a drain port, and are connected to the intake control valve 62and the exhaust control valve 63 supported by the pair of support cases68. The communications of the respective ports are switched by drivingof the intake control valve 62 and the exhaust control valve 63, so thatthe oil is supplied to an advance-side or a retard-side of a variablevalve timing device 91 (refer to FIG. 8).

As shown in FIGS. 7 and 8, the oil control valve unit 61 is fixed to thecylinder 43 from a side by the bolt 78. In this case, a sidewall of thecylinder 43 opens in a circular shape, and the housing main body 67 ofthe valve housing 64 is inserted into the opening part. When the valvehousing 64 is abutted to an inner wall 57 in the cylinder 43, theopening 71 of the housing main body 67 is positionally aligned with ascrew hole 58 formed in the inner wall 57. Then, the banjo joint 82 andthe valve housing 64 are fastened together by the bolt 78, so that theexternal piping 81 and the oil control valve unit 61 are mounted to thecylinder 43.

At this time, the mounting hole 83 of the banjo joint 82 is formed tohave a diameter larger than a shaft part 79 of the bolt 78, so that anoil passage is formed by a gap between the mounting hole 83 of the banjojoint 82 and the shaft part 79 of the bolt 78. Also, the opening 71 ofthe valve housing 64 is formed to have a diameter larger than the shaftpart 79 of the bolt 78, so that an oil passage is formed by a gapbetween the opening 71 of the valve housing 64 and the shaft part 79 ofthe bolt 78. The oil is supplied from the external piping 81 toward theintake control valve 62 and the exhaust control valve 63 through the oilpassages formed around the shaft part 79 of the bolt 78.

The oil is distributed to the intake control valve 62 and the exhaustcontrol valve 63 by using the gap between the mounting hole 83 of thebanjo joint 82 and the shaft part 79 of the bolt 78 and the gap betweenthe opening 71 of the valve housing 64 and the shaft part 79 of the bolt78. The oil passages of the intake control valve 62 and the exhaustcontrol valve 63 are connected to oil passages of a cam housing 59configured to support camshafts 55 through the advance port and theretard port. The oil passages of the cam housing 59 are connected tohydraulic pressure chambers of an intake-side variable valve timingdevice 91 and an exhaust-side variable valve timing device 91 (refer toFIG. 9).

In this way, the oil passages extending from the external piping 81 tothe intake-side variable valve timing device 91 and the exhaust-sidevariable valve timing device 91 are formed by the simple configurationof mounting the oil control valve unit 61 to the cylinder 43. In themeantime, the oil control valve unit 61 is mounted to pass through aninner side of a cam chain 56 configured to transmit power to the pair offront and rear camshafts 55 in the cylinder 43. The configuration ofmounting a member to the inner side of the cam chain 56 is notpreferable from a standpoint of the mounting workability. However, theoil control valve unit 61 is detachably mounted, so that the oil controlvalve unit 61 is not an obstacle upon the mounting of the cam chain 56.

More specifically, in case of the motorcycle 1 (refer to FIG. 1) and thelike, a chain cover is integrated with the cylinder 43. Since it is notpossible to demount only the chain cover from the cylinder 43, when amember is mounted at the inner side of the cam chain 56, the memberbecomes an obstacle upon mounting of the cam chain 56 to the engine 41.For this reason, in the illustrative embodiment, the oil control valveunit 61 is configured to be detachably mounted, and after the cam chain56 is mounted to the engine 41, the valve housing 64 (the housing mainbody 67) of the oil control valve unit 61 is inserted to the inner sideof the cam chain 56. Thereby, any interference does not occur upon themounting of the cam chain 56, and a dead space of the inner side of thecam chain 56 is effectively used.

The valve housing 64 of the oil control valve unit 61 is configured topass through the inner side of the cam chain 56, so that it is possibleto mount the oil control valve unit 61 in the vicinity of the variablevalve timing device 91. Therefore, the external piping 81 from the maingallery 53 (refer to FIG. 9) to the oil control valve unit 61 islengthened, and an internal flow path of the engine 41 from the oilcontrol valve unit 61 to the variable valve timing device 91 isshortened. Thereby, the oil is supplied with high hydraulic pressureinto the oil control valve unit 61 by the external piping 81, and thepressure loss of the oil in the internal flow path of the engine 41 issuppressed to the minimum, so that it is possible to apply the highhydraulic pressure to the variable valve timing device 91.

Also, when the oil control valve unit 61 is mounted to the cylinder 43,the banjo joint 82 is mounted at a more inner side than the valvehousing 64, as seen from the front and rear direction. Since the banjojoint 82 does not protrude more outward than the valve housing 64, asseen from the front and rear direction, an increase in vehicle widthdimension due to the banjo joint 82 is suppressed. Also, the banjo joint82 is mounted at a more inner side than all of the transmission cover45, the main frame 12 and the down frame 13, as seen from the front andrear direction (refer to FIG. 4). Therefore, the banjo joint 82 isprotected from a shock upon turnover of the vehicle body and the otherexternal shock by the transmission cover 45, the main frame 12 and thedown frame 13.

Also, the valve housing 64 is abutted to the inner wall 57 of thecylinder 43, so that the intake control valve 62 and the exhaust controlvalve 63 are spaced from the side surface of the cylinder 43. That is,the solenoids 65 of the oil control valve unit 61 are spaced from theside surface of the engine 41 in the vehicle width direction. For thisreason, the solenoids 65 of the oil control valve unit 61 are notcontacted to the side surface of the cylinder 43, and the increase intemperature of the solenoids 65 due to the heat of the cylinder 43 issuppressed. Therefore, the deterioration of the operationcharacteristics of the oil control valve unit 61 is effectivelysuppressed.

Subsequently, the variable valve timing system is briefly described withreference to FIG. 9. FIG. 9 is a pictorial view of the variable valvetiming system of the illustrative embodiment. In the meantime, althoughthe intake-side and exhaust-side variable valve timing systems aredescribed, the variable valve timing system may be provided at only theintake-side or the exhaust-side. Also, in FIG. 9, for convenience ofdescriptions, the cam chain is shown with the dashed-two dotted line.

As shown in FIG. 9, the variable valve timing system is to vary valvetimings by changing rotation phases of the camshafts 55 relative tocrankshafts (not shown), and includes the hydraulic pressure-typevariable valve timing devices 91. The power from the crankshafts istransmitted to the camshafts 55 by the cam chain 56 via the variablevalve timing devices 91. The variable valve timing device 91 is providedat one end portion of the camshaft 55, and is configured to transmit thepower to the camshaft 55 via the oil supplied therein.

A case 92 of the variable valve timing device 91 is fixed to a sprocket93 on which the cam chain 56 is put, and is configured to rotateintegrally with the sprocket 93. The sprocket 93 is rotatably supportedby one end portion of the camshaft 55 together with the case 92. Also, arotor 95 having vanes 94 is fixed to one end portion of the camshaft 55,and is accommodated to be relatively rotatable inside the case 92. Aplurality of hydraulic pressure chambers is formed inside the case 92,and each vane 94 of the rotor 95 is accommodated in each hydraulicpressure chamber. Each hydraulic pressure chamber is partitioned into anadvance chamber S1 and a retard chamber S2 by each vane 94.

The advance chamber S1 and the retard chamber S2 are configured tocommunicate with the oil paths formed in the camshaft 55 and the camhousing 59 (refer to FIG. 8). When a volume of the advance chamber S1 isincreased by the hydraulic pressure, the rotor 95 is rotated relative tothe case 92 toward the advance side. Thereby, the camshaft 55 fixed tothe rotor 95 rotates, so that the valve timing changes toward theadvance side. On the other hand, when a volume of the retard chamber S2is increased by the hydraulic pressure, the rotor 95 is rotated relativeto the case 92 toward the retard side. Thereby, the camshaft 55 fixed tothe rotor 95 rotates, so that the valve timing changes toward the retardside.

The variable valve timing device 91 is configured to operate by thehydraulic pressure from the oil control valve unit 61. The oil is pumpedup from an oil pan 51 to the main gallery 53 via a filter and the likeby the oil pump 52, and the oil is supplied to the intake control valve62 and the exhaust control valve 63 of the oil control valve unit 61through the external piping 81. Then, the communication states betweenthe intake control valve 62 and exhaust control valve 63 and the portsof the advance port, the retard port, the input port and the exhaustport are switched, so that the variable valve timing is switched to theadvance side or retard side.

At this time, the oil is pumped up from the oil pan 51 to the maingallery 53 by the oil pump 52, so that the oil of high hydraulicpressure is supplied from the main gallery 53 to the oil control valveunit 61 through the external piping 81. Since the external piping 81passes outside the engine, it is not connected to the other hydraulicpressure circuit such as the oil passage in the engine, and the pressureloss of the oil in the external piping 81 is suppressed. By the externalpiping 81 passing outside the engine, the oil is delivered with highhydraulic pressure up to the vicinity of the variable valve timingdevices 91, so that the oil is supplied from the oil control valve unit61 into the engine.

Since the oil control valve unit 61 is mounted in the vicinity of thevariable valve timing devices 91, the oil passage in the engine isshortened, so that the pressure loss of the oil in the oil passage isreduced. Therefore, the oil is supplied from the intake control valve 62and the exhaust control valve 63 to the intake-side and exhaust-sidevariable valve timing devices 91 with high hydraulic pressure, so thatoperating speeds of the variable valve timing devices 91 are increased.Also, it is possible to effectively use the dead space inside the camchain 56 as the oil passage of the oil control valve unit 61, so thatthe oil passage in the engine is not complex.

Subsequently, an operation of mounting the vehicle body frame isdescribed with reference to FIGS. 10 and 11. FIG. 10 depicts an exampleof an operation of mounting the vehicle body frame of the illustrativeembodiment. FIG. 11 depicts another example of the operation of mountingthe vehicle body frame of the illustrative embodiment.

As shown in FIG. 10, the mounting space 49 of the oil control valve unit61 exists on a moving locus upon mounting of the vehicle body frame 10.The transmission cover 45 bulges from a side of the engine 41, and arear part of the vehicle body frame 10 is formed with the body frame 15(the rear part of the main frame) so as to surround (so as to turnaround rearward) a part of the bulging part of the transmission cover 45from the rear. Also, the front part of the vehicle body frame 10 isbifurcated into the main frame 12 and the down frame 13, and themounting space 49 of the oil control valve unit 61 is secured so thatthe oil control valve unit 61 is positioned between the main frame 12and the down frame 13.

In this case, the vehicle body frame 10 is mounted to the engine 41 inan oblique direction shown with an arrow so that the main frame 12 doesnot interfere with the bulging part of the transmission cover 45.However, upon the mounting of the vehicle body frame 10, since themounting space 49 of the oil control valve unit 61 exists on the movinglocus of the down frame 13 shown with the dashed-two dotted line, thevehicle body frame 10 interferes with the oil control valve unit 61. Forthis reason, in the illustrative embodiment, the oil control valve unit61 is detachably mounted to the outer surface of the engine 41 avoidingthe vehicle body frame 10. After the vehicle body frame 10 is mounted tothe engine 41 while suppressing the interference of the main frame 12with the transmission cover 45, the oil control valve unit 61 can bemounted from a side of the cylinder 43.

Thereby, it is possible to suppress the interference between the vehiclebody frame 10 and the oil control valve unit 61, so that a degree ofmounting freedom of the oil control valve unit 61 is secured. Meanwhile,in the illustrative embodiment, after mounting the vehicle body frame 10to the engine 41, the oil control valve unit 61 is mounted to the sidesurface of the cylinder 43. However, the present invention is notlimited thereto. When there is the mounting space 49 of the oil controlvalve unit 61 so as to avoid the moving locus of the vehicle body frame10, the vehicle body frame 10 may be mounted in a state where the oilcontrol valve unit 61 is mounted to the side surface of the cylinder 43.

For example, as shown in FIG. 11, the oil control valve unit 61 and thebulging part of the transmission cover 45 are mounted between aforefront part 15 a of the body frame 15 below the transmission cover 45and a last part 13 a of the down frame 13, in the front and reardirection of the vehicle body. When the vehicle body frame 10 isdownward mounted from the upper of the engine 41 in the verticaldirection, moving loci L1, L2 are depicted by the forefront part 15 a ofthe body frame 15 and the last part 13 a of the down frame 13. Since themoving loci L1, L2 deviate from the oil control valve unit 61 and thetransmission cover 45, it is possible to mount the vehicle body frame 10to the engine 41 in the state where the oil control valve unit 61 ismounted to the side surface of the cylinder 43.

As described above, according to the illustrative embodiment, the downframe 13, which is a part of the vehicle body frame 10, is positionedbetween the radiator 47 and the oil control valve unit 61, and the heatfrom the radiator 47 is shielded by the down frame 13, so that thedeterioration of the operation characteristics of the oil control valveunit 61 due to the increase in temperature is suppressed. Also, the oilcontrol valve unit 61 is protected from the flying stones in front ofthe vehicle body by the down frame 13.

In the meantime, in the illustrative embodiment, the parallelfour-cylinder engine has been exemplified as the engine. However, thepresent invention is not limited thereto. The configuration of theengine is not particularly limited. For example, the engine may also bea single cylinder engine, a parallel two-cylinder engine, a V-shapedengine, a horizontal opposed type engine, an in-line two-cylinderengine, or the like.

Also, in the illustrative embodiment, the twin spar frame has beenexemplified as the vehicle body frame. However, the present invention isnot limited thereto. The vehicle body frame may have any shape capableof securing the mounting space of the oil control valve unit for theengine. For example, the vehicle body frame may be configured by acradle frame.

Also, in the illustrative embodiment, the oil control valve unit ismounted to the right side of the engine. However, the oil control valveunit may be mounted to the left side of the engine.

Also, in the illustrative embodiment, the radiator has been exemplifiedas the heat exchanger. However, the present invention is not limitedthereto. The heat exchanger may be any configuration capable of radiatethe heat carried by the liquid such as cooling water and oil, in frontof the engine. For example, the heat exchanger may be configured by anoil cooler, or a radiator and an oil cooler.

Also, in the illustrative embodiment, the oil control valve unit ismounted at the side of the cylinder. However, the present invention isnot limited thereto. The oil control valve unit has only to be mountedat the side of the engine. For example, the oil control valve unit maybe mounted at a side of the engine case.

Also, in the illustrative embodiment, the oil control valve unitoverlaps the down frame, as seen from the front and rear direction.However, the present invention is not limited thereto. The oil controlvalve unit preferably overlaps the down frame, as seen from the frontand rear direction. However, the oil control valve unit may not overlapthe down frame, as seen from the front and rear direction.

Also, in the illustrative embodiment, the facing interval between thepair of right and left main frames is narrowed at the rear of the oilcontrol valve unit, so that the air can easily flow to the rear of theoil control valve unit. However, the present invention is not limitedthereto. For example, the oil control valve unit may not be exposed, asseen from the rear, inasmuch as the oil control valve unit can besufficiently cooled.

Also, in the illustrative embodiment, the oil control valve unitoverlaps the main frame, as seen from the front and rear direction.However, the present invention is not limited thereto. The oil controlvalve unit preferably overlaps the main frame, as seen from the frontand rear direction. However, the oil control valve unit may not overlapthe main frame, as seen from the front and rear direction.

Also, in the illustrative embodiment, the down frame is configured tosupport the front side of the engine. However, the present invention isnot limited thereto. The support position of the down frame to theengine is not particularly limited inasmuch as it is possible to securethe mounting space of the oil control valve unit for the engine.

Also, in the illustrative embodiment, the width of the down frame iswidened in the front and rear direction from the support position of theengine toward the head pipe. However, the present invention is notlimited thereto. That is, the shape of the down frame is notparticularly limited.

Also, in the illustrative embodiment, the solenoid valve has beenexemplified as the oil control valve unit. However, the presentinvention is not limited thereto. The oil control valve unit may haveany configuration capable of controlling the hydraulic pressure to thevariable timing device of the engine. That is, the type of the valve isnot particularly limited.

Also, in the illustrative embodiment, the down frame passes through thefront side of the EX cam axis center, and the main frame passes throughthe rear side of the IN cam axis center. However, the present inventionis not limited thereto. For example, the down frame may be configured topass through a rear side of the EX cam axis center, and the main framemay be configured to pass through a front side of the IN cam axiscenter, inasmuch as it is possible to secure the mounting space of theoil control valve unit at the side of the engine.

Also, in the illustrative embodiment, the oil control valve unitincludes the intake control valve and the exhaust control valve.However, the present invention is not limited thereto. For example, theoil control valve unit may include any one of the intake control valveand the exhaust control valve.

Also, in the illustrative embodiment, the intake control valve and theexhaust control valve are vertically spaced from each other withhorizontal postures. However, the present invention is not limitedthereto. For example, the intake control valve and the exhaust controlvalve are preferably vertically spaced from each other with horizontalposture but the postures and mounting places of the intake control valveand the exhaust control valve are not particularly limited.

Also, in the illustrative embodiment, the radiator hose extends rearwardfrom the radiator. However, the present invention is not limitedthereto. For example, the radiator hose may be mounted so as to avoidthe oil control valve unit, and the mounting route of the radiator hoseis not particularly limited.

Also, in the illustrative embodiment, the radiator hose has beenexemplified as the hose extending from the heat exchanger. However, thepresent invention is not limited thereto. For example, when the heatexchanger is an oil cooler or the like, an oil hose may be used as thehose.

Also, in the illustrative embodiment, the oil control valve unit and themain gallery are connected by one external piping. However, the presentinvention is not limited thereto. The oil control valve unit and themain gallery may be connected by a plurality of external pipings. Forexample, the external pipings may be connected to each of the intakecontrol valve and the exhaust control valve.

Also, in the illustrative embodiment, the mounting route of the externalpiping is not particularly limited. The external piping may have anyconfiguration capable of connecting the oil control valve unit and themain gallery.

Also, in the illustrative embodiment, the external piping overlaps thedown frame, as seen from the front and rear direction. However, thepresent invention is not limited thereto. The external piping preferablyoverlaps the down frame, as seen from the front and rear direction.However, the external piping may not overlap the down frame, as seenfrom the front and rear direction.

Also, in the illustrative embodiment, the external piping overlaps themain frame, as seen from the front and rear direction. However, thepresent invention is not limited thereto. The external piping preferablyoverlaps the main frame, as seen from the front and rear direction.However, the external piping may not overlap the main frame, as seenfrom the front and rear direction.

Also, in the illustrative embodiment, the external piping is configuredto pass the inner side of the radiator hose. However, the presentinvention is not limited thereto. The external piping may have anyconfiguration capable of connecting the oil control valve unit and themain gallery, and may be configured to pass through an outer side of theradiator hose.

Also, in the illustrative embodiment, the upper part of the transmissioncover is inclined so that the interval with the oil control valve unitbecomes wider forward. However, the present invention is not limitedthereto. The upper part of the transmission cover may have any shapecapable of securing the mounting space of the oil control valve unit.

Also, in the illustrative embodiment, the oil control valve unit ismounted at the inner side than the transmission cover, the main frameand the down frame, as seen from the front and rear direction. However,the present invention is not limited thereto. The oil control valve unitmay be mounted at the more inner side than any one of the transmissioncover, the main frame and the down frame, as seen from the front andrear direction.

Also, in the illustrative embodiment, the shape of the valve housing isnot particularly limited. That is, the valve housing may have any shapecapable of supplying the oil in the external piping to the variablevalve timing device.

Also, in the illustrative embodiment, the valve housing and the banjojoint, which is a circular ring-shaped joint, are together fastened tothe cylinder by the bolt. However, the method of fastening the valvehousing and the banjo joint is not particularly limited.

Also, in the illustrative embodiment, the external piping is connectedto the valve housing via the banjo joint provided at the leading end ofthe external piping. However, the present invention is not limitedthereto. For example, the external piping may be connected to the valvehousing by inserting the external piping into the valve housing.

Also, in the illustrative embodiment, the valve housing is formed withthe guide surfaces configured to guide the banjo joint to the valvehousing so that the mounting hole of the banjo joint coincides with theopening of the valve housing. However, the present invention is notlimited thereto. For example, the valve housing may not be formed withthe guide surfaces.

Also, in the illustrative embodiment, the banjo joint is mounted at themore inner side than the main frame, the down frame and the transmissioncover, as seen from the front and rear direction. However, the presentinvention is not limited thereto. The banjo joint is preferably mountedat the more inner side than the main frame, the down frame and thetransmission cover, as seen from the front and rear direction. However,the banjo joint may be mounted at a more outer side than the main frame,the down frame and the transmission cover, as seen from the front andrear direction.

Although the respective illustrative embodiments of the presentinvention have been described, the other illustrative embodiments of thepresent invention obtained by entirely or partially combining theillustrative embodiment and modified embodiments are also possible.

Also, the illustrative embodiment of the present invention is notlimited to the above-described illustrative embodiment, and can bediversely changed, replaced and modified without departing from thetechnical spirit of the present invention. Also, when the technicalspirit of the present invention can be implemented with other methods byadvance in technology or by the other deriving technology, the presentinvention can be implemented using the methods. Therefore, the claimscover all implementations that can be included in the technical spiritof the present invention.

Also, in the illustrative embodiment, the present invention has beenapplied to the motorcycle. However, the present invention is not limitedthereto. That is, the present invention can be appropriately applied tothe other vehicles having the oil control valve unit mounted thereto,for example, a special machine such as a jet ski bike, a lawn trimmer,an outboard motor and the like, in addition to an automatic four-wheeledvehicle and a buggy-type motor tricycle.

In the below, features of the illustrative embodiment of the presentinvention are summarized.

The mounting structure of the oil control valve unit described in theillustrative embodiment is a mounting structure of an oil control valveunit configured to control a hydraulic pressure to a variable valvetiming device of an engine, wherein the engine is supported by a vehiclebody frame, wherein a heat exchanger is mounted in front of the engine,wherein the oil control valve unit is mounted at a side of the engine,and wherein a part of the vehicle body frame is arranged between the oilcontrol valve unit and the heat exchanger in a front and rear direction.According to this configuration, the part of the vehicle body frame ispositioned between the heat exchanger and the oil control valve unit,and heat from the heat exchanger is shielded by the part of the vehiclebody frame, so that deterioration of operation characteristics of theoil control valve unit due to an increase in temperature is suppressed.Also, the oil control valve unit is protected from flying stones infront of a vehicle body by the part of the vehicle body frame.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the oil control valve unit overlapsthe part of the vehicle body frame, as seen from the front and reardirection. According to this configuration, since the front of the oilcontrol valve unit is covered by the part of the vehicle body frame, theheat shield effect by the vehicle body frame is increased, and the oilcontrol valve unit is effectively protected from flying stones in frontof the vehicle body.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the vehicle body frame includes apair of right and left main frames extending rearward from a head pipe,and a pair of right and left down frames extending downward from thehead pipe, and the oil control valve unit is mounted in a mounting spacebetween the main frames and the down frames. According to thisconfiguration, it is possible to effectively use a space between themain frames and the down frames, as the mounting space of the oilcontrol valve unit. Also, the oil control valve unit is protected fromflying stones by the main frames and the down frames.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the pair of right and left mainframes extends obliquely downward from the head pipe toward the rear,and a facing interval between the pair of right and left main frames isnarrowed at the rear of the mounting space of the oil control valveunit, so that the oil control valve unit is exposed, as seen from therear. According to this configuration, the air flow is not hindered atthe rear of the oil control valve unit, so that the heat is not retainedin the mounting space of the oil control valve unit. Therefore, the oilcontrol valve unit is effectively cooled upon traveling.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the oil control valve unit overlapsthe main frame, as seen from above. According to this configuration, themain frame functions as a rain shelter, so that a damage of the oilcontrol valve unit due to the rainwater is prevented.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the down frames are configured tosupport a front side of the engine. According to this configuration, theoil control valve unit and the down frame are spaced, so that the heatis difficult to be retained in the mounting space of the oil controlvalve unit and a surrounding temperature of the mounting space can belowered.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the down frames are configured tosupport a front side of a cylinder of the engine, a width of each downframe is formed to be wider in the front and rear direction from asupport position of the cylinder toward the head pipe, and the oilcontrol valve unit is mounted in the mounting space between the mainframe and the down frame at a side of the cylinder. According to thisconfiguration, even when the width of the down frame is formed to bewider in the front and rear direction from the support position of thecylinder toward the head pipe, it is possible to secure the mountingspace of the oil control valve unit at the side of the cylinder.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the oil control valve unit includesa solenoid valve, and a solenoid-side of the solenoid valve facesrearward. According to this configuration, since the solenoid is spacedfrom a radiator, the deterioration of operation characteristics of theoil control valve unit due to an increase in temperature of the solenoidis suppressed.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, an axis center of the solenoidfaces horizontally or obliquely upward toward the rear. According tothis configuration, foreign matters such as contaminations and the likeare difficult to be deposited on the solenoid, so that a damage of thesolenoid is prevented.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the solenoid of the solenoid valveis spaced from a side surface of the engine in a vehicle widthdirection. According to this configuration, the solenoid of the oilcontrol valve unit is spaced from a side surface of the cylinder, sothat an increase in temperature of the solenoid due to the heat of thecylinder is suppressed.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the engine includes a pair of frontand rear camshafts, the down frames are configured to pass through afront side of an axis center of the front camshaft, and the main framesare configured to pass through a rear side of an axis center of the rearcamshaft. According to this configuration, the mounting space of the oilcontrol valve unit is largely secured, so that the heat is difficult tobe retained in the mounting space and the surrounding temperature of themounting space can be thus lowered.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the engine is provided with atransmission, a transmission cover configured to cover the transmissionfrom a side is formed with a bulging part bulging laterally, the mainframe has a rear part of the main frame configured to surround a part ofthe bulging part from the rear, and the oil control valve unit and thebulging part are arranged between a forefront part of the rear part ofthe main frame below the bulging part and a last part of the down frame,in the front and rear direction of a vehicle body. According to thisconfiguration, it is possible to mount the vehicle body frame to theengine in a state where the oil control valve unit is mounted to theside surface of the cylinder.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the oil control valve unit includesan intake control valve configured to control an intake-side valvetiming and an exhaust control valve configured to control anexhaust-side valve timing. According to this configuration,deterioration of operation characteristics of the intake control valveand the exhaust control valve due to the increase in temperature issuppressed, and the intake control valve and the exhaust control valveare protected from the flying stones in front of the vehicle body.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the intake control valve and theexhaust control valve are spaced from each other with a connection partof an external piping for oil supply being interposed therebetween.According to this configuration, the heat is difficult to be retainedbetween the intake control valve and the exhaust control valve, so thatit is possible to lower the surrounding temperature of the mountingspace of the oil control valve unit.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the intake control valve and theexhaust control valve are vertically spaced from each other withhorizontal postures with the connection part being interposedtherebetween. According to this configuration, since the intake controlvalve and the exhaust control valve are vertically aligned, an increasein vehicle width dimension of a main body of the vehicle body issuppressed. Also, since the intake control valve and the exhaust controlvalve are longitudinally aligned with horizontal postures, both thecontrol valves are evenly cooled by the air flow upon the traveling.

In the mounting structure of the oil control valve unit described in theillustrative embodiment, preferably, the heat exchanger is a radiator, aradiator hose configured to deliver cooling water from the radiator tothe engine extends rearward from the radiator, and the oil control valveunit is mounted above the radiator hose. According to thisconfiguration, the oil control valve unit is cooled by the cooling waterin the radiator hose. Also, the oil control valve unit is protected fromthe flying stones below the vehicle body by the hose.

The motorcycle described in the illustrative embodiment includes themounting structure of the oil control valve unit. According to thisconfiguration, it is possible to precisely control the hydraulicpressure to the variable valve timing device of the motorcycle by theoil control valve unit of which the deterioration of operationcharacteristics is suppressed and which is protected from the flyingstones in front of the vehicle body.

What is claimed is:
 1. A motorcycle comprising: a vehicle body frame; anengine with a variable valve timing device, the engine supported by thevehicle body frame; and an oil control valve unit configured to controla hydraulic pressure to the variable valve timing device of the engine,wherein a heat exchanger is mounted in front of the engine, wherein theoil control valve unit is mounted at a side of the engine, wherein apart of the vehicle body frame is arranged between the oil control valveunit and the heat exchanger in a front and rear direction of themotorcycle, wherein the vehicle body frame comprises a pair of right andleft main frames extending rearward from a head pipe, and a pair ofright and left down frames extending downward from the head pipe, andwherein the oil control valve unit is mounted in a mounting spacebetween the main frames and the down frames.
 2. The motorcycle accordingto claim 1, wherein the oil control valve unit overlaps the part of thevehicle body frame, as seen from the front and rear direction.
 3. Themotorcycle according to claim 1, wherein the pair of right and left mainframes extends obliquely downward from the head pipe toward the rear,and wherein a facing interval between the pair of right and left mainframes is narrowed at the rear of the mounting space of the oil controlvalve unit, so that the oil control valve unit is exposed, as seen fromthe rear.
 4. The motorcycle according to claim 1, wherein the oilcontrol valve unit overlaps the main frame, as seen from above.
 5. Themotorcycle according to claim 1, wherein the down frames are configuredto support a front side of the engine.
 6. The motorcycle according toclaim 1, wherein the down frames are configured to support a front sideof a cylinder of the engine, and a width of each down frame is formed tobe wider in the front and rear direction from a support position of thecylinder toward the head pipe, and wherein the oil control valve unit ismounted in the mounting space between the main frame and the down frameat a side of the cylinder.
 7. The motorcycle according to claim 1,wherein the oil control valve unit comprises a solenoid valve, andwherein a solenoid-side of the solenoid valve faces rearward.
 8. Themotorcycle according to claim 7, wherein an axis center of the solenoidfaces horizontally or obliquely upward toward the rear.
 9. Themotorcycle according to claim 7, wherein the solenoid of the solenoidvalve is spaced from a side surface of the engine in a vehicle widthdirection of the motorcycle.
 10. The motorcycle according to claim 1,wherein the engine comprises a pair of front and rear camshafts, andwherein the down frames are configured to pass through a front side ofan axis center of the front camshaft, and the main frames are configuredto pass through a rear side of an axis center of the rear camshaft. 11.The motorcycle according to claim 1, wherein the engine is provided witha transmission, wherein a transmission cover configured to cover thetransmission from a side is formed with a bulging part bulginglaterally, wherein the main frame has a rear part configured to surrounda part of the bulging part from the rear, and wherein the oil controlvalve unit and the bulging part are arranged between a forefront part ofthe rear part of the main frame below the bulging part and a last partof the down frame, in the front and rear direction.
 12. The motorcycleaccording to claim 1, wherein the oil control valve unit comprises anintake control valve configured to control an intake-side valve timingand an exhaust control valve configured to control an exhaust-side valvetiming.
 13. The motorcycle according to claim 12, wherein the intakecontrol valve and the exhaust control valve are spaced from each otherwith a connection part of an external piping for oil supply beinginterposed therebetween.
 14. The motorcycle according to claim 13,wherein the intake control valve and the exhaust control valve arevertically spaced from each other with horizontal postures with theconnection part being interposed therebetween.
 15. The motorcycleaccording to claim 1, wherein the heat exchanger is a radiator, whereina radiator hose configured to deliver cooling water from the radiator tothe engine extends rearward from the radiator, and wherein the oilcontrol valve unit is mounted above the radiator hose.